Precisely constructing charge-asymmetric dual-atom Fe sites supported on hollow porous carbon spheres for efficient oxygen reduction

Abstract

Transition group metal catalysts showing atomic dispersion are on the rise as affordable electrocatalysts for the oxygen reduction reaction (ORR) in fuel cell batteries, but their activity in acidic media remains constrained. In this work, we present a new catalyst (Fe₂–S₁N₅/SNC) for the ORR. The active site of catalysis composed of two charge-asymmetric iron atoms can regulate the adsorption energy of intermediate species (OH*) in the ORR, thereby enhancing the kinetics of the ORR. Furthermore, the use of hollow porous carbon spheres as a support for the catalysis enhances substance transport during the ORR. Fe₂–S₁N₅/SNC exhibits remarkable electrochemical activity in the ORR, displaying a remarkably high half-wave potential of 0.829 V vs. RHE, and it also demonstrates impressive stability, as the half-wave potential only decreases by 26 mV after 5000 cycles in a 0.1 M HClO₄ solution. Therefore, this study offers valuable insights into the low-cost metal catalyst design for the ORR, specifically the precise construction of active sites.